AP-PCR Fingerprinting for Detection of Genetic Damage Caused by Polycyclic Aromatic Hydrocarbons

Exposure of organisms to genotoxic chemicals results in the formation of stable, covalently bound adducts between the chemical (or one of its metabolites) and the DNA, these adducts may cause mutations and cytogenetic changes. The primary effects of such exposure (i.e. adduct formation) and subsequent effects on the DNA (cytogenetic damage, mutation) may be monitored using a number of assays of varying sensitivity and specificity. Recent developments in molecular biology offer new possibilities for detecting DNA damage. We examined whether DNA fingerprinting by arbitrarily primed polymerase chain reaction (AP-PCR) can reveal differences in the DNA fingerprints of rats and shore crabs exposed to benzo[a]pyrene in the laboratory and of crabs from control and from polluted areas. The results indicate that differences between control and exposed animals were detectable and that DNA fingerprinting by AP-PCR offers a useful alternative biomarker assay for the detection of the genotoxic effects of environmental pollutants.     

Mercury exposure in female artisanal small-scale gold miners (ASGM) in Mongolia: An analysis of human biomonitoring (HBM) data from 2008

Background

Many poor in developing countries have turned to artisanal small-scale gold mining (ASGM) in an attempt to improve their situation. However, the mercury used to extract gold from ore is discharged in vaporized form into the environment, where it poses a hazard for human health.

Methods

As part of an environmental epidemiological study in Mongolia—to evaluate the burden of environmental mercury contamination—urine, blood and hair samples were collected from residents of areas with or without mercury contamination. A total of 200 blood, urine and hair samples were analyzed for mercury and divided into three subgroups according to mercury content: (1) occupational exposure (high/medium); (2) environmental exposure (low); and (3) no exposure. Internal mercury distributions of the subgroups were compared using the Kruskal-Wallis and Mann-Whitney U-test. The Chi-square test and likelihood ratio proportion were used to compare the findings with threshold limits.

Results

The highest values and greatest differences were seen in the urine samples (p < 0.001, Kruskal-Wallis). The occupational group showing the highest exposure with a median mercury level of 4.36 μg/l (control group: 0.10 μg/l, p < 0.001), 7.18 μg/g creatinine and 12 results above the threshold limit HBM I (Human Biomonitoring I). Even participants from the low-exposure subgroup showed elevated mercury levels (median 2.88 μg/l urine and 2.98 μg/g creatinine, p < 0.001), with 10 individuals above the HBM I threshold limits.

Discussion

The body burden resulting from the use of mercury in artisanal gold mining is high not only in the miners themselves, an increased mercury hazard was also found for inhabitants of mining areas who were not actively involved in mining. Public health support measures are urgently needed to alleviate the situation.     

MONITORING POLYCYCLIC AROMATIC COMPOUNDS IN ENVIRONMENTAL AND WORKPLACE SAMPLES USING CONVENTIONAL METHODS AND THE AMES MUTAGENICITY ASSAY OF THEIR NITRATED DERIVATIVES

The development of sensitive methods for monitoring polycyclic aromatic compounds (PACs) has been a central focus of industrial hygiene studies in those industries where workers are exposed to petroleum oils, bitumen fumes or fuel combustion products. The work reported here focuses on one aspect of that effort—workplace monitoring of airborne PAC levels in the hot-mix asphalt paving industry. During the manufacture, transport, and roadway application of hot-mix asphalt (HMA), workers are exposed to low levels of bitumen fumes emanating from the hot product. Over the last twenty-five years, concerns about the health effects of these exposures have prompted numerous studies of the airborne levels of asphalt fumes in the workplace. By and large, these studies have shown that PAC exposures are extremely low—often below the detection limits of standard analytical techniques. For the present study, we have used standard industrial hygiene methods, together with a newer, biologically based assay called the Nitration Assay to measure relative ambient levels of fumes and/or PACs in various paving workplace settings. The latter assay was also used to test bitumen fumes generated in the laboratory by a new “microfuming” technique and to determine specific activities of the 16 PAHs designated by the US EPA as priority pollutants. The Nitration Assay takes advantage of two properties of 3–7-ring PACs: the ease with which they can be chemically nitrated and the high mutagenic potency of the nitrated products in the Ames Salmonella mutagenicity assay. Measurements of fumes and nitratable PAC levels on seven different hot-mix paving jobs showed reasonable correlations between the various methods, as well as patterns of exposure consistent with proximity to fume source.     

Concentration of selected persistent organic pollutants in blood from delivering women in South Africa

Environmental exposure to persistent organic pollutants (POPs) may cause detrimental health effects in the population with the developing foetus and infants being at highest risk. This paper reports on the findings of the pilot study that took place in seven geographical regions of South Africa, 96 pregnant women admitted for delivery participated in the study. The following selected POPs were analysed in maternal plasma: 15 polychlorinated biphenyls (PCBs) congeners (IUPAC No. 28, 52, 99, 101, 105, 118, 138, 149, 153, 156, 170, 180, 183, 187, 194); six DDT metabolites (dichlordiphenyltrichloroethane p,p'-DDT and o,p'-DDT; diphenyldichloroethylene p,p'-DDE and o,p'-DDE, dichlorophenylethane p,p'-DDD o,p'-DDD) and other pesticides such as hexachlorocyclohexanes (α-HCH, β-HCH, γ-HCH), hexachlorobenzene (HCB), heptachlor, chlordanes (t-CD and c-CD), nanochlors (t-NC and c-NC) and mirex.The overall results showed large regional differences with the rural site having the lowest levels for all measured contaminants. The levels of PCB congeners were found to be low in all samples and across all sites. DDT metabolites were detected in most participants of this study and large regional differences were evident. Two malaria endemic sites, where indoor residual spraying (IRS) with DDT takes place to control malaria vector, were included in the study. The highest levels of DDTs were measured in the coastal malaria site (Indian Ocean) with geometric means of 5177 ng/g lipid and 1797 ng/g lipid for p,p'-DDE and p,p'-DDT, and 1966 ng/g lipid and 726 ng/g lipid for p,p'-DDE and p,p'-DDT in inland malaria site. γ-HCH was found to be elevated overall, except for the urban community; the highest levels were measured in the inland and coastal malaria sites. p,p'-DDT and γ-HCH were however not correlated, indicating different sources. The high DDT levels in the malaria spraying regions as well as the elevated γ-HCH levels are of concern and call for extended monitoring of women and children in selected regions.     

北京市中小学生5种食品添加剂的内暴露水平分析

目的 了解北京市中小学生尿液中5种食品添加剂的内暴露水平。方法 2016年9月,在北京2个区的中小学收集900份学生尿液样本,采用液相色谱-串联质谱法测定5种食品添加剂（苯甲酸、安赛蜜、甜蜜素、糖精和4-己基间苯二酚）含量,按照年龄组计算每日估计摄入量（EDI）,并评估其存在的健康风险。结果 全部尿液样本中均检测到甜蜜素和糖精,96.3%的样本中检测到安赛蜜。甜蜜素的中位浓度（4 788.5 ng/mL）明显高于其他4种食品添加剂（苯甲酸235.9 ng/mL,安赛蜜92.6 ng/mL,糖精84.1 ng/mL,4-己基间苯二酚7.6 ng/mL）。7~12岁学生尿液中苯甲酸浓度极显著高于13~17岁年龄组的学生（P<0.001）;13~17岁年龄组学生尿液中安赛蜜、糖精和4-己基间苯二酚浓度极显著高于7~12岁学生（P<0.001）;13~17岁年龄组女生尿液中糖精浓度极显著高于同年龄组男生（P<0.001）。5种食品添加剂的中位EDI分别为：苯甲酸3.48 μg/kg·BW/d、安赛蜜1.36 μg/kg·BW/d、甜蜜素69.01 μg/kg·BW/d、糖精1.22 μg/kg·BW/d、4-己基间苯二酚0.11 μg/kg·BW/d。结论 本研究中北京市中小学生广泛暴露于5种食品添加剂,部分高暴露儿童甜蜜素EDI高于每日允许摄入量（ADI）,存在一定的健康风险,其他4种添加剂暴露水平远低于ADI,总体处于安全水平。     

THE SIGNIFICANCE OF POLYCYCLIC AROMATIC HYDROCARBONS AS ENVIRONMENTAL CARCINOGENS. 35 YEARS RESEARCH ON PAH—A RETROSPECTIVE

In vivo studies with laboratory animals as well as in vitro studies with bacteria and mammalian cell cultures have demonstrated that the mutagenic and/or carcinogenic properties of numerous PAHs require metabolic transformation. Metabolism of PAHs has been explored in vitro using cellular microsomal fractions, mammalian cell cultures and later genetically engineered cells expressing cytochromes P450 from several species including humans.

Balancing the carcinogenic potential of some environmental matrices (vehicle exhaust, condensate of hard coal combustion effluents, cigarette smoke condensate, used motor oil) after separation into sub-fractions evidenced that the carcinogenic effect may be attributed almost exclusively to PAH. Mixtures of well-known carcinogenic PAH in concentrations as present in these matrices, however, did not explain the total biological effect. Thus, it had been speculated that either very potent unknown carcinogens are still hidden in the PAH fraction, or that synergistic effects (enzyme induction) play a significant role.

In parallel to these carcinogenicity studies, the metabolism of various PAHs has been investigated in rat liver microsomes from untreated animals as well as from animals pre-treated with inducers of cytochrome P450. It was found that even non-carcinogenic PAHs possess a significant inducing potential. Moreover, in several mammals a highly species-specific metabolism of PAH could be observed allowing a critical view to the extrapolation from animal experiments to the human situation. This was further confirmed by experiments with mammalian cell cultures including human ones as well as by metabolic studies with genetically engineered Chinese hamster V79 cells singularly expressing various cytochrome P450 enzymes from a number of different species (human, rat, mouse, fish). With these cell lines metabolic studies were carried out with a larger number of PAHs as substrates including phenanthrene, pyrene, chrysene, benzo[a]anthracene, benzo[c]phenanthrene, benzo[a]pyrene, dibenzo[a,l]pyrene, and benzo[c]chrysene.

Based on the metabolism results, analytical methods have been developed to determine urinary biomarkers of human PAH exposure. Human biomonitoring studies have been performed with different occupationally exposed individuals as well as within smokers and non-smokers of the general population. Endogenous PAH exposure levels and changes in the urinary excreted metabolic profile depending on exposure level have been determined.     

Comparison of Different Genotoxic Tests for Biological Monitoring of Coke Oven Workers. Preliminary Results

Chemical by-products of coke production are classified by IARC as carcinogenic in humans. Polycylic aromatic hydrocarbons (PAH) are the main compounds involved in carcinogenic and mutagenic activities of coke oven smokes, but many other compounds are present in emissions and could be involved in these activities. PAH analysis of the atmosphere indicated external contamination, but is not sufficient to evaluate the risk for exposed workers. The aim of this study was to evaluate relationship between atmospheric analysis of PAH and genotoxic markers in coke oven workers'white cells compared to controls. One hundred fifty-five exposed workers'samples were analyzed. They were selected in 5 coke production sites using a complete questionnaire allowing one to exclude all confounding factors. Two equal groups of smokers and nonsmokers were analysed. Analysis of chromosomal aberrations (CA), sister chromatid exchange (SCE), micronucleus (MN) and DNA-adduct formation using ³²P-postlabelling were performed on leucocytes. Each worker was equiped with an individual pump during the shift, for analysis of 16 PAH.

All markers were strongly modified by smoking habits. In smokers, CA, SCE and MN were not influenced by exposure to PAH. The number of DNA-adducts was increased with PAH concentration. In non smokers, we have observed an increaseof breaks / cells and of the percentage of cells with aberrations. Number of MN and SCE were unchanged. The number and the amount of DNA-adducts were strongly increased in exposed workers. DNA-adducts appear to be the best marker for genotoxic risk assessment.